1. Field of the Invention
The present invention relates to an image display apparatus for performing a fluorescent display operation by using a multi-electron beam source having a plurality of electron-emitting devices wired in the form of a matrix and, more particular, to an image display apparatus using a surface-conduction type electron-emitting device as an electron-emitting device.
2. Related Background Art
Conventionally, two types of devices, namely hot and cold cathode devices, are known as electron-emitting devices. Examples of cold cathode devices are surface-conduction type electron-emitting devices, field emission type electron-emitting devices (to be referred to as FE type electron-emitting devices hereinafter), and metal/insulator/metal type electron-emitting devices (to be referred to as MIM type electron-emitting devices hereinafter).
Known examples of the FE type electron-emitting devices are described in W. P. Dyke and W. W. Dolan, "Field Emission", Advance in Electron Physics, 8, 89 (1956) and C. A. Spindt, "Physical Properties of thin-film field emission cathodes with molybdenum cones", J. Appl. Phys., 47, 5248 (1976). FIG. 71 is a sectional view of an FE type electron-emitting device. Referring to FIG. 71, reference numeral 81 denotes a substrate; 101, an emitter wiring layer made of a conductive material; 102, an emitter cone; 103, an insulating layer; and 104, a gate electrode. In the FE type, a voltage is applied between the emitter cone 102 and the gate electrode 104 to emit electrons from the distal end portion of the emitter cone 102.
A known example of the MIM type electron-emitting devices is described in C. A. Mead, "Operation of Tunnel-Emission Devices", J. Appl. Phys., 32,646 (1961). FIG. 72 is a sectional view of an MIM type electron-emitting device. Referring to FIG. 72, reference numeral 105 denotes a lower electrode made of a metal; 106, a thin insulating layer having a thickness of about 100 .ANG.; and 107, an upper electrode made of a metal and having a thickness of about 80 to 300 .ANG.. In the MIM type, a voltage is applied between the upper electrode 107 and the lower electrode 105 to emit electrons from the surface of the upper electrode 107.
A known example of the surface-conduction type electron-emitting devices is described in, e.g., M. I. Elinson, "Radio Eng. Electron Phys.", 10, 1290 (1965) and other examples to be described later. The surface-conduction type electron-emitting device utilizes the phenomenon that electron emission is caused in a small-area thin film, formed on a substrate, by passing a current parallel to the film surface. The surface-conduction type electron-emitting device includes electron-emitting devices using an Au thin film (G. Dittmer, "Thin Solid Films", 9,317 (1972)), an In.sub.2 O.sub.3 /SnO.sub.2 thin film (M. Hartwell and C. G. Fonstad, "IEEE Trans. ED Conf.", 519 (1975)), a carbon thin film (Hisashi Araki et al., "Vacuum", vol. 26, No. 1, p. 22 (1983), and the like, in addition to an SnO.sub.2 thin film according to Elinson mentioned above.
FIG. 70 is a plan view of the surface-conduction type electron-emitting device according to M. Hartwell et al. as a typical example of the structures of these surface-conduction type electron-emitting devices. Referring to FIG. 70, reference numeral 81 denotes a substrate; 84, a conductive thin film made of a metal oxide formed by spattering. This conductive thin film 84 has an H-shaped pattern, as shown in FIG. 70. An electron-emitting portion 83 is formed by performing an electrification process (referred to as a forming process to be described later) with respect to the conductive thin film 84. Referring to FIG. 70, an interval L is set to 0.5 to 1 mm, and a width W is set to 0.1 mm. The electron-emitting portion 83 is shown in a rectangular shape at the center of the conductive thin film 84 for the sake of illustrative convenience, however, this does not exactly show the actual position and shape of the electron-emitting portion.
In the above surface-conduction type electron-emitting devices by M. Hartwell et al., typically the electron-emitting portion 83 is formed by performing electrification process called the forming process for the conductive thin film 84 before electron emission. According to the forming process, electrification is performed by applying a constant DC voltage which increases at a very low rate of, e.g., 1 V/min., to both ends of the conductive film 84, so as to partially destroy or deform the conductive film 84, thereby forming the electron-emitting portion 83 with an electrically high resistance. Note that the destroyed or deformed part of the conductive thin film 84 has a fissure. Upon application of an appropriate voltage to the conductive thin film 84 after the forming process, electron emission is performed near the fissure.
The above surface-conduction type electron-emitting devices are advantageous because they have a simple structure and can be easily manufactured. For this reason, many devices can be formed on a wide area. As disclosed in Japanese Patent Laid-Open No. 64-31332 filed by the present applicant, a method of arranging and driving a lot of devices has been studied.
Regarding applications of surface-conduction type electron-emitting devices to, e.g., image forming apparatuses such as an image display apparatus and an image recording apparatus, charged beam sources and the like have been studied.
As an application to image display apparatuses, in particular, as disclosed in the U.S. Pat. No. 5,066,833 and Japanese Patent Laid-Open No. 2-257551 filed by the present applicant, an image display apparatus using the combination of an surface-conduction type electron-emitting device and a phosphor which emits light upon irradiation of an electron beam has been studied. This type of image display apparatus is expected to have more excellent characteristic than other conventional image display apparatuses. For example, in comparison with recent popular liquid crystal display apparatuses, the above display apparatus is superior in that it does not require a backlight since it is of a light emissive type and that it has a wide view angle.
A display apparatus preferably has a delta arrangement in which red (R), green (G), and blue (B) pixels are arranged in a triangular form, as shown in FIG. 73A, because this structure makes the vertical stripes inconspicuous unlike a stripe arrangement. As shown in FIG. 73A, the same color pixels on two lines vertically adjacent to each other are shifted a 1.5 pitch in the row direction. In order to manufacture a display apparatus having such a delta arrangement, column wiring layers 54 are arranged in zig-zag lines as shown in FIG. 73B (Japanese Patent Publication No. 3-64046). Referring to FIG. 73B, reference numeral 55 denotes a row wiring layer; and 86, a electron-emitting device.
In the display apparatus having the delta arrangement, the zig-zag arrangement of the column wiring layers makes the manufacturing process complicated as compared with the case wherein the column wiring layers are straight. In addition, disconnection of wiring layers tend to occur, and the wiring resistance increases.